Hydraulic pumps



June 7, 1966 H. D. FANsHAwE 3,254,605

HYDRAULIC PUMPS Filed April 8, 1964 A TTORAZEYIS 3,254,605 HYDRAULiC PUMPS United States Patent O Hew Dalrymple Fanshawe,vNorth Berwick, East Lothian,

Scotland, assignor to F.N.R.D. Limited, London, England, a British company Filed Apr. 8, 1964, Ser. No. 358,232 Claims priority, application Great Britain, Apr. 8, 1963, 13,959/ 63 5 Claims. (Cl. 10S- 49) actuating liud is a liquid as distinguished from a gaseous Huid, such as steam.

The invention relates in particular to pumping arrangements comprising a number of hydraulically-operated piston-type pumps, the inputs and outputs respectively of which are in parallel connection. In operation, oil under pressure is arranged to be applied to the piston of each pump for the delivery strokes. Though the effective area of the piston on the oil side may dier from that on the medium side,`perhaps by the area of a piston-rod, the amount of pressurised oil required will approach the amount of medium pumped by each piston on its delivery stroke. For the parallel operation of pumps, each requires its own quantity of oil, Vand normally, therefore, the quantities of oil required are multiple. It is an object of the invention to make provision for reduction of the amount of oil necessary for pumping any given amount of medium with parallelled pumps.

In accordance with one aspect of the invention, the pumping arrangement is adapted to operate on substantially only that amount of oil necessary for the operation of a single pump. Thus the pumping arrangement may comprise a plurality of hydraulically-operated piston-type reciprocating pumps connected to operate with inputs and outputs respectively in parallel, and the path of the oil for actuating the piston of one pump is arranged to be in series with the path for actuating the piston of another pump. In this way the pumping rate of any arrangement may be increased for a given maximum rate of l ow of actuating oil.

In accordance with another aspect of the invention a reciprocating pump arrangement for pumping fluids cornprises two hydraulically-operated piston-type pumps, the inlets to the pumps for a medium to be pumped being connected to a common inlet manifold for said medium and the outlets being connected to va common outlet manifold, feed means to one of the pumps for leading pressurised oil for actuating the piston of the pump, outlet means for said actuating oil leaving said rst pump, feed means to the other of said pumps for leading actuating oil to the piston of said other pump, outlet means for said ractuating oil leaving said other pump, and means connecting said outlet means for said rst pump to said feed means for the other pump, whereby said pressurised actuating oil may be led through said pumps in series.

If the pumps -are single-acting or simple double-acting, then the delivery of each to the common outlet will be intermittent, because of the reversals of motion of theV pistons, and it will be desirable to include ancillary means, such as those described in the specification accompanying co-pending patent application Serial No. 358,216, for

4ensuring continuity of delivery. In addition, unless the ICC two pumps are perfectly synchronised there may be la diculty in that termination of the strokes of either pump will interrupt the ilow of actuating oil through.

both pumps, and this will, of course, le'ad to the possibility of interruptions of flow of actuating oil to both pumps being doubled; where there are more than two pumps the interruptions may be accordingly increased. Here again, therefore, it will be desirable to include means, as similarly disclosed in the specification accompanying said co-pending application, for `ensuring continuous availability of actuating oil for each pump. Preferably each pump is double-acting with two linked pistons adapted to operate to pump alternately; such an arrangement is a very compact one, since much of the actuating gea for the pistons does not have to be duplicated.

Where the medium to be pumped is corrosive, or one comprising a suspension of abrasive solids, corrosion or excessive wear of the pistons or of Vtheir associated cylinders may be avoided by arranging that each piston is adapted to move the medium through the movement of a exible diaphragm separated from the face ofthe piston remote from the actuating oil'thereof by a substantially fixed volume of la trapped liquid.

It is appreciated that in a pumping arrangement according to the invention the inlet pressure of the actuating oil for the rst pump must approximate to a multiple of that necessary for operating the pumps were the actuating oil paths in parallel, but in any circumstances the actuating oil is made available from the output of one or more variable delivery oil pumps driven by a prime mover or prime movers yof a certain maximum horsepower. VIf the available horsepower is insutiicient to provide the maximum through-put capacity demanded at half, onethird, one quarter, as the case may be, of the maximum rated pressure of the oil pumps, then full benefit can be taken of the invention in reducing the oil pumping capacity needed, the maximum medium through-put being met with half, one-third, one quarter, as may be, of the oil pumping capacity, still working below the maximum rated pressure.

Where the actuating oil would stand to be contaminated by mixture with the medium being pumped, should a tiexible diaphragm between the two rupture, it will normally be preferable in such cases to arrange that the outlet for the actuating oil for the' second pump is connected to a pressure line at, for instance, 350 Vp.s.i.; this boost pressure ensuring that any leakage past the piston will be oil outwardly and not medium inwardly. It also ensures that the fixed volume of liquid trapped between piston and diaphragm will never decrease; any tendency for the diaphragm to over-flex due to leakage may be countered by means automatically operated by the diaphragm itself to vent this liquid. No make-up means are necessary to guand against inward bursting of the diaphragm on the suction stroke.

In order that the invention may be better understood, one embodiment thereof will now be described by way of example with reference to the accompanying diagrammatic drawing; the drawing shows an arrangement of two linked-piston double-acting pumps larranged with their respective intakes and delivery outlets arranged in parallel, and the arrangement is shown also for operation according tothe invention described in the said co-pending patent application, that is with ancillary means for providing continuity of delivery during reversal periods of the pistons.

In the drawing the parallel pumps 1 and 2 are shown feeding a delivery connection 3 for the pumped medium through lines 4 and 5, and the medium is fed to the pumps through connections 6 and 7, from supply line 8.

Pressurized oil for actuating the pistons of the pump is derived from a connection 9 to a supply which may be at about 2350 p.s.i. for a delivery pressure about 1000 p.s.i., and is connected through line 10 with the spool valve 11 for energising pump 1, the relief of actuating oil from this pump taking place through the connection 12, cross-over valve 13 and connection 14 to the spool valve 15 which controls the energising of pump 2. Relief of actuating oil from pump 2 occurs through connections 16 to the oil return 17, whence it is fed back to the oil reservoir, at about 350 p.s.i. for re-eirculation.

The spool valves 11 and 15 are actuated by pilot valves 1S and 19 respectively, which are operated as the respective pistons near the ends of their suction strokes, as indicated. The pilot valves control application of a separate, pilot, pressurised-oil supply to the one end or the other of the spool valve of each pump to cause the actuating oil for each to ilow to one or other of the pumping pistons, the pressure of oil falling about 2000 p.s.i. in approximately equal steps, in pump 1 from 2350 p.s.i. to about 1350 p.s.i. and in pump 2 from about 1350 p.s.i. to 350 p.s.i., thus ensuring that each pump delivers at about 1000 p.s.i. into the common delivery outlet 3. Operation of the biased ancillary piston means 20 and 21 with their associated diaphragm chambers 22 and 23, to ensure continuity of supply of pumped medium at the delivery connection 3 and continuity of demand for oil from connections 9 and 14, is described in the co-pending patent application hereinbefore referred to.

These features, however, have no direct bearing on the present invention.

The accompanying drawing also includes step valves and alternative connections which, by transference of the cross-over valve 13 and re-adjustment of connections of high pressure actuating oil and the oil return, as explained in the aforementioned co-pending patent application, enable the system to be changed over to provide for the higher pressure operation of the pump 2 and lower pressure operation of pump 1 to provide for more even wear of the system; otherwise there will be a tendency for the actuating mechanism for pump 1, if operating under higher pressure all the time, to suifer greater wear than that of pump 2. Nevertheless such a facility is not mandatory.

I claim:

1. A pumping arrangement for pumping a fluid medium, comprising a plurality of hydraulically-operated piston-type pumps each having a medium inlet and a medium outlet, a medium supply line, a medium delivery line, the inlets of said pumps being connected to said medium supply line in parallel and the outlets of said pumps being connected to said delivery line in parallel, and means for so feeding actuating liquid to said pumps that the arrangement operates on only substantially the quantity of actuating liquid required for operating a single said pump.

2. A pumping arrangement for pumping a fluid medium, comprising a plurality of hydraulically-operated piston-type pumps each having a medium inlet and a medium outlet, means for so connecting said pumps that they operate with their medium inputs and outputs respectively in parallel, and means for so supplying actuating liquid to said pumps that the path of the actuating liquid for the piston of one said pump is in series with the path of the liquid for actuating the piston of each of the other pumps.

3. A reciprocating pump arrangement for pumping a fluid medium, comprising two hydraulically-operated piston-type pumps each having a'medium inlet and a medium outlet, a common inlet manifold to which the inlets to said pump are connected and a common outlet manifold to which the outlets from said pumps are connected, feed means for leading pressurised liquid to one of said pumps foractuating the piston of that pump, outlet means for actuating liquid leaving said one pump, feed means for leading actuating liquid to the piston of the other of said pumps, outlet means for actuating liquid leaving said other pump, and means connecting said outlet means for said one pump to said feed means for the other pump, whereby said pressurised actuating liquid -may be led through said two pumps in series.

References Cited by the Examiner UNITED STATES PATENTS 642,237 1/1900 Lane 103-49 FOREIGN PATENTS 2,731 1891 Great Britain.

ROBERT M. WALKER, Primary Examiner. 

1. A PUMPING ARRANGEMENT FOR PUMPING A FLUID MEDIUM, COMPRISING A PLURALITY OF HYDRAULICALLY-OPERATED PISTON-RYPE PUMPS EACH HAVING A MEDIUM INLET AND A MEDIUM OUTLET, A MEDIUM SUPPLY LINE, A MEDIUM DELIVERY LINE, THE INLETS OF SAID PUMPS BEING CONNECTED TO SAID MEDIUM SUPPLY LINE IN PARALLEL AND THE OUTLEST OF SAID PUMPS BEING CONNECTED TO SAID DELIVERY LINE IN PARALLEL, AND MEANS FOR SO FEEDING ACTUATING LIQUID TO SAID PUMPS 